Vacuum reducer valve

ABSTRACT

A three-chamber vacuum reducer valve is used in the distributor spark advance control system to provide a source of vacuum for advancing the spark firing during engine overheat conditions. The source of vacuum is greater than the ported spark vacuum found upstream of the throttle plate in a carburetor intake and less than the manifold vacuum. One input to the reducer is the manifold vacuum and the other input is atmospheric pressure which are combined by means of a regulator in the valve for producing an output vacuum which is reduced from the manifold vacuum.

United States Patent 1191 Martin Mar. 19, 1974 [5 VACUUM REDUCER VALVE3,612.018 10/1971 Soberski 123/117 A [75] Inventor: Frank J. Martin, AnnArbor, Mich.

' 1 Primary Examiner-William R. Cline [73] Ass1gnee: ChryslerCorporation, Highland 1 Park, Mich.

1- STRACT [22] Filed: Mar. 14, 1973 A three-chamber vacuum reducer valveis used in the PP N05 340,991 distributor spark advance control systemto provide a 7 source of vacuum for advancing the spark firing dur- 52us. c1. 137/116.5 123/117 A ehghe hverheat The vacuum 51 1111. C1 6051111/01; F02d 5/02 is gram than the Pmed Spark vacuum fhhd 58 Field ofSearch 137/1 16.3 116.5' Stream hmme Plate a intake ahd 1237117 lessthan the manifold vacuum. One input to the reducer is the manifoldvacuum and the other input is [56] References Cited atmospheric pressurewhich are combined by means of a regulator in the valve for producing anoutput UNITED STATES PATENTS, vacuum which is reduced from the manifoldvacuum. 2.883.998 4/l959 Bloughton 137/1163 3,411,522 11/1968 Golden etal. 137/1165 4 Claims, 7 Drawing Figures PATENTEUHAH 19 m 3797151 2 sum2 OF 2 J L1 M m 7/ VACUUM REDUCER VALVE BACKGROUND OF INVENTION l. Fieldof Invention This invention relates to vacuum valves in general and moreparticularly to a vacuum reducer valve for producing an output vacuum ata predefined vacuum level below an input vacuum.

2. Prior Art U. S. Pat. No. 2,883,998 teaches a vacuum system having adiaphragm operated vacuum control valve for maintaining a steady andconstant vacuum in the system. When the vacuum in the system becomesless than the controlled value, the diaphragm operates to open a poppetvalve thereby connecting a vacuum source to the syytem. When the systemhas reached the desired vacuum level the diaphragm operates to close thepoppet valve. If the vacuum in the system rises beyond the desiredlevel, the diaphragm operates to admit atmospheric pressure into thesystem thereby reducing the vacuum level. This valve operates tomaintain the vacuum at a constant level.

SUMMARY OF INVENTION It is a principal object of the invention tomaintain the output of a vacuum reducer valve at a predetermined vacuumdifferential from an input source.

It is another object of the invention to isolate the vacuum source andthe atmospheric source from each other in a vacuum reducer valve.

These and other objects will become apparent from the followingdrawings, description and claims of a three-chamber vacuum reducervalve. One chamber is connected to a source of atmospheric pressure andis interconnected through a valve seat and dump valve actuated to asecond chamber. The second chamber is connected to a vacuum utilizationmeans and the third chamber, isolated from the second chamber by meansof a flexible diaphragm having a valve seat in line and cooperating withthe dump valve actuator, is connected to a source .of vacuum.

The dump valve actuator is responsive to the source of atmosphericpressure and to the vacuum source to maintain the vacuum in the secondchamber at a predetermined differential level from the input vacuum.This level is determined by means of a regulator in the third chamberwhich operates to move the diaphragm between an atmospheric source and avacuum source.

DESCRIPTION OF THE DRAWINGS In the drawings:

FIG. 1 is a schematic of a carburetor system incorporating the vacuumreducer valve controlling the distributor advance vacuum motor;

FIG. 2 is a top view of the vacuum reducer valve;

FIG. 3 is a sectional view taken along line 33 of FIG. 2;

FIG. 4 is a plan view of the inside of the cover member of the valve ofFIG. 2;

FIG. 5 is a graph of the operation of the vacuum reducer valve;

FIG. 6 is a sectional view similar to that of FIG. 3 with the diaphragmin an intermediate position;

FIG. 7 is a sectional view similar to that of FIG. 3 with the diaphragmin the second extreme position.

DETAILED DESCRIPTION Referring to the figures by the characters ofreference there is illustrated in FIG. 1 a schematic of a carburetorsystem as may be used with an internal combustion engine. The purpose ofthe system of FIG. 1 is to control the distributor advance vacuum motorthereby controlling the firing point of the fuel in the cylinders of theengine. An air cleaner 10 is positioned over the top of a carburetorintake conduit 12 for cleaning the air which flows along the conduitthrough the venturi section 14 past the throttle plate 16 and to themanifold 18. Secured to the air cleaner on the clean air side is aconduit 20 which may be rigid or flexible for supplying clean air atatmospheric pressure to one input 22 of the vacuum reducer valve 24 ofthe present invention. A second input 26 to the vacuum reducer valve isconnected by means of another conduit 28 to a vacuum source 30 in theair intake conduit 12. This vacuum source 30 is downstream from thethrottle plate 16 and supplies a vacuum source hereinafter referred toas the manifold vacuum. The output 31 of the vacuum reducer valve 24 isconnected by means of a third conduit 32 to one input 34 of a thermalswitch 36 and from there to the distributor advance vacuum motor 38.Another input 40 to the thermal switch 36 is connected by means of aconduit 42 to the ported spark vacuum source 44 in the carburetor intakeconduit 12.

In an internal combustion engine, the manifold vacuum is at a largevalue in terms of inches of mercury at idle condition of the engine anddecreases to substantially zero vacuum at wide open throttle condition.It is the function of the vacuum reducer valve 24 to supply an outputvacuum at a predetermined vacuum differential level from that of themanifold vacuum or input vacuum. In a decreasing vacuum condition, inorder to provide this output vacuum it is necessary to mix or dilute,under controlled conditions, the manifold .vacuum as supplied to thevacuum reducer valve 24 with air at atmospheric pressure. In anincreasing vacuum condition, the reducer valve 24 supplies vacuum fromthe vacuum source 30. This reduced vacuum is supplied through a thermalvacuum switch 36 to the distributor advance vacuum motor 38. The thermalvacuum switch 36, in one embodiment, is sensitive to engine coolanttemperatures and will connect the output of vacuum reducer valve 24 tothe distributor advance vacuum motor 38 whenever the engine coolanttemperatures reach an abnormally high temperature. Normally the vacuumbeing applied to the distributor advance vacuum motor 36 is a much lowervacuum such as that at the ported spark output 44 of the carburetorintake conduit 12 upstream of the throttle plate 16 as illustrated inFIG. I or from the venturi section 14 of the intake conduit. In eithercase, this vacuum is much lower than the manifold vacuum. However, in asystem wherein the thermal switch 36 senses that the cooling systemtemperatures are above a predetermined level, it is necessary to advancethe firing of fuel in the cylinders of the engine thereby lowering theengine temperature. This is accomplished by the thermal switch 36switching the higher vacuum output from the vacuum reducer valve 241into the distributor advance vacuum motor causing the spark to beadvanced. Under these conditions, advancing the spark results in earlierdetonation of the fuel and, therefore, a more efficient conversion offuel into mechanical energy instead of heat energy.

As previously indicated, during normal driving conditions, thedistributor vacuum advance is controlled directly by the ported sparkvacuum 44, however, under certain load, speed or weather conditions,this is affectively a retard operation increasing the heat rejection tothe engine coolant and causing the engine to run hotter. Under theseconditions, the distributor spark control must be advanced to reducethis added heat load. If the thermal switch 36 connected the manifoldvacuum to the distributor vacuum advance, an excessive amount of advancewill be produced and the engine will knock. The vacuum reducer'valve 24provides a vacuum that is a predetermined vacuum differential less thanthe manifold vacuum to advance the engine firing enough to lower itscoolant temperature but not advancing the engine firing enough to causethe engine to knock.

Referring to FIG. 3, there is illustrated a crosssectional view of thepreferred embodiment of the vacuum reducer valve 24. In general, thevalve has a first chamber 46 with an input port 22, a second chamber 48with an output port 31 which is the output port of the valve 24 and athird chamber 50 with an input port 26. lnterposed in the space'betweenand separating the second and third chambers 48 and 50 is a flexiblediaphragm 52 with a centrally located flow passageway 54 and valve seat56. Located in the first chamber 48 is a dump valve 58 controlling thefluid communication between the first and second chambers and, as willbe shown, also controls the fluid communication between the second andthird chambers. Located in the third chamber 50 is a regulator means 60biasing the diaphragm 56 in a first position.

The first chamber 46 is defined by a tubular cylindrical inside covermember 62 enclosed at one end. Located along the axis of the covermember 62 is the input port 22 having a nipple extension 64 forconnecting a conduit thereto. The open end of the chamber is enclosed bymeans of a bearing plate 66 having a centrally located aperture axiallyin line with the input port 22. Positioned within the first chamber 46and extending through and beyond the aperture in the bearing plate 66 isthe dump valve member or spool 58. The dump valve member 58 cooperateswith an O-ring 68 for sealing the first chamber preventing fluid flowout of the aperture. Additionally, biasing means 70 cooperates with thespool and the enclosed surface sf the first chamber for biasing thespool 58 toward said aperture.

The second chamber 48 is defined by a tubular cylindrical member 72enclosed at one end. In the preferred embodiment, this cylindricalmember 72 is also the outside cover member and the inside cover member62 nests within and is bonded to a cylindrical cavity 74 therein. Beforebonding the two cover members 62 and 72 together, a resilient gasketmember 76 is positioned between the bearing plate 66 and the bottom ofthe cavity 74 forming a seal. Axially positioned in the enclosed end ofthe second chamber and aligned with the output port of the first chamberis the input port 78 to the second chamber. Positioned along the surfaceof the enclosed end are a plurality of raised spaced apart radiallyextending diaphragm stop members 80. Between each adjacent stop member80 is a fluid flow passageway 82 extending from the input port 78radially to the side walls of the chamber 48.

The output port 31 of the valve 24 is formed in the enclosed end of thesecond chamber 48 and is adjacent the side wall of the chamber. A nippleextension 34 extends the output port 31 providing means to attach aconduit thereto to a vacuum utilization means. The particularpositioning of the output port 31 in the second chamber 48 is notlimited to the enclosed end of the chamber but by this positioning theoverall size of the valve 24 in general, and the chamber 48, inparticular, is compact.

The third chamber 50, which in the preferred embodiment is the largestchamber, is formed by a cavity 86 in the main body member 88 of thevalve. An input port 26 is positioned in the end wall of the body member88 and is extended outwardly of the body member by a nipple extension 90for attaching a conduit thereto from a vacuum source. The open end ofthe body member 88 is enclosed by the flexible diaphragm 52 held inplace around its periphery by the rims of the body member 88 and outsidecover member 72.

The flexible diaphragm 52 has an axially located button 92 having avacuum flow passageway 54 therethrough. The side of the diaphragm button92 adjacent to the second chamber forms a valve seat 56 for the dumpspool 58 extending from said first chamber 46. A spring receiving cupmember 94 is positioned against the broadside of the diaphragm 52 facingthe third chamber and is secured thereto by the button 92. The springreceiving cup member 94 receives a regulating means 60 or compressionspring that is located in the third chamber 50 and biases the diaphragmin a'normal first position against the diaphragm stop member 80 in thesecond chamber 48. A second set of diaphragm stop members 96 are spacedaround the input port 26 in the third chamber 50 for preventing thediaphragm 52 from sealing the input port 26.

Referring to FIG. 5, there is graphically illustrated the operation ofthe vacuum reducer valve 24. Along the abscissa 98 of the graph, thevacuum input to the third chamber is plotted in inches of mercury andalong the ordinate 100 of the graph, the vacuum output of the reducervalve 24 is plotted in inches of mercury. The reducer valve 24 isdesigned to produce a vacuum output that is predetermined vacuum levellower, V on the graph, than the input vacuum. Thus, for a vacuum V onthe input, the output is (V V In the present embodiment, V is equal to3.5 inches of mercury.

Operation of Reducer The reducer valve diaphragm 52 has three basicoperating positions. These three positions are illustrated in FIGS. 3,6, and 7. The first position is illustrated in FIG. 3 and is the normalor rest position where the vacuum source is at zero inches of mercury.The diaphragm 52 is biased against the stop members 80 in the secondchamber 48 and the dump valve 58 is held open by the diaphragm 52. Inthis first position, there is fluid communication between the input port22 to the first chamber 46 through the fluid flow passageways 82 to theoutput port 31 of the second chamber 48.

As the vacuum source increases from zero inches of mercury, the force ofthe atmospheric pressure entering the first chamber pushes against thedump spool 58 and the diaphragm 52 to move the diaphragm away from thefirst position. During this portion of the diaphragm move, the dumpvalve spool 58 and the valve seat 56 in the diaphragm remain in a sealedrelationship. The biasing spring 70 in the first chamber 46 functions tomaintain the dump valve spool 58 and the valve seat 56 in this sealedrelationship.

When the vacuum at the vacuum source reaches the desired vacuumdifferential, V in FIG. 5, the reducer valve 24 is in its secondposition as illustrated in FIG. 6. In this position, both the first andthird chambers 46 and 50 are sealed from fluid communication with anyother chamber in the reducer valve 24. This second position is theequilibrium position of the reducer valve whenever the input vacuumexceeds the output vacuum by the predetermined vacuum differential V Thecompression spring force 60 in the third chamber 50 is at its workinglength maintaining the vacuum level in the second chamber 48 at thepredetermined vacuum differential less than the vacuum source in saidthird chamber 50.

As the input vacuum increases along the abscissa in FIG. 5 beyond thepoint V,, the diaphragm 52 begins to modulate about the second positionand will move toward a third position as illustrated in FIG. 7. Thisposition is a temporary position in that whenever the pressure or vacuumin the second chamber 48, the output vacuum, for a given input vacuumfalls on the graph plot of FIG. 5, the regulating means 60 will move thediaphragm 52 back to the second position. If the vacuum sum of theatmospheric pressure and the vacuum in the second chamber 48 is greaterthan the sum of the input vacuum and the calibration of the regulatingmeans 60, the diaphragm will modulate toward the first position. Thismodulation will bring the dump valve spool 58 and the diaphragm valveseat 56 into a sealed relationship closing off fluid communicationbetween the third and second chambers 50 and 48. The regulating means 60will then continue to move the diaphragm 52 toward the first positionuntil the dump valve spool 58 and the O-ring 68 seal is broken admittingatmospheric pressure to the second chamber 48. When the output vacuumfalls on the graph plot, the diaphragm 52 returns to its second positionas illustrated in FIG. 6.

If suddenly a large vacuum was placed on the input 26 to the thirdchamber 50 which was large enough to collapse the regulating means 60,the diaphragm stops 96 around the input port 26 would prevent theflexible diaphragm 52 from sealing the port. As soon as the spring 60recovered, the diaphragm would move toward its second position to bringthe output to its desired value.

There has thus been shown and described a vacuum reducer valve 24 formaintaining the output of the valve within a predetermined vacuumdifferential from the input vacuum source. As the input vacuum varies,the flexible diaphragm 52 cooperates with a dump valve 58 to modulatethe output vacuum providing the correct mixture of atmospheric pressureand vacuum to maintain the desired vacuum output.

What is claimed is:

l. A vacuum reducer valve for regulating the vacuum supplied to a vacuummotor within a predetermined vacuum differential of a vacuum source,said reducer comprising:

a first chamber having an input port for connection to a source ofatmospheric pressure and an output port;

a second chamber having an input port connected to the output port ofsaid first chamber and having an output port for connection to autilization means;

a third chamber having an input port for connection to a source ofvacuum pressure;

a flexible diaphragm having a centrally located flow passageway integralwith a valve seat, said diaphragm sealingly separating said second andthird chambers whereby said flow passageway provides for fluidcommunication between said second and third chambers;

stop means located in said second chamber for locating said diaphragm ina first position;

a dump valve located in said first chamber and extending through saidoutput port of said first chamber and biased into contact with saidvalve seat in said diaphragm, said dump valve responsive to the sourceof atmospheric pressure connected to said input port of said firstchamber for moving said diaphragm from said first position closing saidflow. passageway therein and fluidly interconnecting said first andsecond chambers to a second position for closing the output port of saidfirst chamber and before opening said flow passageway and fluidlyinterconnecting said second and third chambers; and

regulating means located in said third chamber and connected to saiddiaphragm responding to said vacuum source to modulate said diaphragmthereby opening and closing said flow passageway therein for maintainingthe vacuum level in said second chamber within a predetermined vacuumdifferential less than the vacuum source connected to said thirdchamber.

2. A vacuum reducer valve according to claim 1 wherein said regulatingmeans is a compression spring calibrated at its working length tomaintain the vacuum level in said second chamber at a predeterminedvacuum differential less than the vacuum source in said third chamber.

3. A vacuum reducer valve according to claim 1 additionally including asecond set of stop means located around the input port of said thirdchamber for preventing said diaphragm from sealing said input port.

4. A vacuum reducer valve according to claim 1 wherein said first,second and third chambers are integrally connected forming a unitaryvalve body.

1. A vacuum reducer valve for regulating the vacuum supplied to a vacuummotor within a predetermined vacuum differential of a vacuum source,said reducer comprising: a first chamber having an input port forconnection to a source of atmospheric pressure and an output port; asecond chamber having an input port connected to the output port of saidfirst chamber and having an output port for connection to a utilizationmeans; a third chamber having an input port for connection to a sourceof vacuum pressure; a flexible diaphragm having a centrally located flowpassageway integral with a valve seat, said diaphragm sealinglyseparating said second and third chambers whereby said flow passagewayprovides for fluid communication between said second and third chambers;stop means located in said second chamber for locating said diaphragm ina first position; a dump valve located in said first chamber andextending through said output port of said first chamber and biased intocontact with said valve seat in said diaphragm, said dump valveresponsive to the source of atmospheric pressure connected to said inputport of said first chamber for moving said diaphragm from said firstposition closing said flow passageway therein and fluidlyinterconnecting said first and second chambers to a second position forclosing the output port of said first chamber and before opening saidflow passageway and fluidly interconnecting said second and thirdchambers; and regulating means located in said third chamber andconnected to said diaphragm responding to said vacuum source to modulatesaid diaphragm thereby opening and closing said flow passageway thereinfor maintaining the vacuum level in said second chamber within apredetermined vacuum differential less than the vacuum source connectedto said third chamber.
 2. A vacuum reducer valve according to claim 1wherein said regulating means is a compression spring calibrated at itsworking length to maintain the vacuum level in said second chamber at apredetermined vacuum differential less than the vacuum source in saidthird chamber.
 3. A vacuum reducer valve according to claim 1additionally including a second set of stop means located around theinput port of said third chamber for preventing said diaphragm fromsealing said input port.
 4. A vacuum reducer valve according to claim 1wherein said first, second and third chambers are integrally connectedforming a unitary valve body.